U.S. Pat. No. 3,617,233 (Mumford), which was assigned to a predecessor of the assignee of this application, the disclosure of which is incorporated by reference herein, describes a glass forming machine of the I.S. type, which is a type of forming machine that is widely used in forming various types of hollow glass containers. As described in the '233 patent or as is otherwise known, an I.S. machine has a multitude of side-by-side machine sections, such as six, eight, ten or even twelve sections, and containers are formed in each section, usually two, three, or four at a time, in a two-stage process. In the first of the stages, preforms of the containers, which are often called parisons or blanks, are formed by pressing or blowing gobs of molten glass in a first set of molds, often called blank molds, with each parison being formed in an inverted orientation, that is, with its open end down. Each set of blank molds is made up of a separable pair of semi-cylindrical mold elements, which remain in end to end contact with one another throughout the blank molding step.
During the forming of glass parisons in an I.S. machine blank mold, the "finish" portion of each parison, which is the threaded or otherwise configured closure receiving portion at the open end, is formed by a separate annular neck mold, which is often referred to as a neck ring, each of which is made up of a separable pair of generally semi-cylindrical elements. The neck rings for each I.S. machine section are carried in a neck ring mechanism and remain in closing contact with the parisons at the conclusion of the blank molding step, when the elements of the blank molds separate to allow the parisons to be transferred to a second set of molds, often referred to as blow molds, for the blowing of parisons into containers in the final desired shape of the containers. The containers are held by the neck rings during their transfer from the blank molds to the blow molds, and the transfer is effected by inverting the neck ring mechanism through an arc of 180.degree. to present the parisons, which remain grasped by the neck rings throughout the transfer step, at the blow molds, the parisons now being in upright orientations, with the finishes at the top, as a result of the inverting step.
At the blow mold station, each parison is blown into its final desired configuration in a second set of molds, each set of blow molds being made up of a separable pair of semi-cylindrical elements, which remain in end to end contact with one another throughout the blow molding step. At the conclusion of the blow molding step, the separable semi-cylindrical blow mold elements are separated, and the finished containers are removed for further processing.
From time to time during the useful lives of sets of I.S. machine molds, both blank molds and blow molds, it is necessary to remove each mold set for repair. During normal repair operations, the face or pad surfaces adjacent to their respective cavities are machined, as well as welding of glass contacting surfaces of the mold elements to replace material lost through abrasion from prior usage. However, these repair procedures can lead to an out of roundness condition in various diametral surfaces of the molds, such as the baffle engaging surfaces of blank molds (the baffle is identified by reference numeral 15 in the aforesaid '233 patent) and the bottom plate engaging surfaces of the blow molds. It is important that these diametral surfaces be as round as possible for proper manufacture of glass containers, and it is the repair of these otherwise out of round surfaces to which the present invention is directed.